1. Field of the Invention
Embodiments of the present invention generally relate to a field of vehicle technology, and more particularly, to a vehicle step apparatus and a motor assembly thereof.
2. Description of the Related Art
A vehicle step apparatus mounted on a chassis of a vehicle is used to assist passengers to get on or off the vehicle. An extending and retracting device of the vehicle step apparatus is driven by a motor via a reducing mechanism. Because a mounting space of the vehicle step apparatus is limited, it is required that the vehicle step apparatus has a small size. There are two kinds of reducing mechanisms for the current vehicle step apparatus.
The first kind of reducing mechanism is a combination of a worm-and-worm wheel reducing mechanism and a cylindrical gear reducing mechanism. The first kind of reducing mechanism has defects of a low protection level and a large size, and thus is difficult to be mounted on a vehicle body.
The second kind of reducing mechanism is a combination of a worm-and-worm wheel reducing mechanism and another worm-and-worm wheel reducing mechanism. The second kind of reducing mechanism has defects of a high manufacture cost and a large size, and thus is difficult to be manufactured and to be mounted on the vehicle body.
Moreover, because a worm of the reducing mechanism has a great axial force, an axial gap of the worm increases after a period of usage and due to abrasion caused therein, so that the transmission efficiency is decreased, and the noise during reversal is increased.